R25 is correct for the particular circuit layout I traced - the one that shows it fitted in a Fender Jazz bass
There are several different versions of this circuit board - some have a unity buffer stage first, BUT the one I traced has the gain stage with the relatively large hf rolloff capacitor C4 fitted.
Without this 1n capacitor the hiss would be very annoying at full treble boost
The Fender American Deluxe bass PDF circuit board image shows R25 and C12 even though only one of these components is fitted. On the board which I traced only C12 is marked on the silkscreen, BUT if you look at what is fitted it is clearly NOT a capacitor but a 2.2M resistor.
The inclusion of C9 (470n or 0.47u electro) on the circuit means there is now no direct DC path from the second stage op amp output to the inverting input - this is WHY C12 is replaced by R25, a 2.2M ohm resistor
With the gain stage resistor and capacitor values AND with all the tone controls set to mid way, the frequency response is -3dB down at approx 23Hz and 30KHz - it has a stage gain of 6.6dB (or x4.62 AC voltage gain)
The pictures of the Fender preamp which you can purchase for US$60 on ebay is NOT this circuit - it has a buffer and several different value resistors fitted in the tone control section - it does NOT have the 470n capacitor fitted to the wiper of the bass control pot AND it has the C12 220p capacitor fitted instead of the 2.2M resistor
Back to the Fender American Deluxe bass circuit
I will publish some response curves showing full boost and full cut for each of the three bands of the tone controls soon.
Of course there is a good deal of interaction between these controls, which is normal for such a simple baxandall circuit.
To achieve proper separation involves three separate op amp stages
For example: if you have full treble boost and then turn up the midrange it will actually cut the treble boost response down
All for now - have work to do